1. Field of the Invention
The present invention relates to a video camera including a camera housing, a first objective, through which light from a scene to be picked up is guidable into the camera housing, and a semiconductor sensor field, on which light from the scene to be picked up is able to be cumulated. It further relates to an adapter for a video camera, including an adapter housing and an objective, through which light from a scene to be picked up is guidable into the adapter housing.
2. Description of the Related Prior Art
The invention deals with the problem of depth of focus. Since video cameras exist, attempts are made to copy the “look” of a celluloid film picture. For the following three reasons, this fails: firstly, the resolution of film is currently still much higher than that of video. Secondly, the contrast range of film is substantially higher, and thirdly, the depth of focus of a 35 mm film is distinctly lower.
The last-mentioned reason may rather seem like a disadvantage for a layman, but in effect is exactly the opposite for an expert. Low depth of focus is of extraordinary importance especially in making cinema films. However, what is felt as especially “film-like”, namely a quickly decreasing depth of focus, is not typical for all of the existing film formats at all. “Super 8” or “16 mm” are—due to the small imaging area—in the worst case well-focused like a video. However, also films on these formats are not yet felt as especially “film-like”. The everyday perception of what is “film-like” is characterized by the continuous consumption of materials of the field of the 35 mm film: All of the Hollywood movies, all advertising films, all of the big video clips are still formed exclusively on this format. And this consumption has characterized the perception. For example, a “Tatort” filmed on a 16 mm film, will hardly be perceived as especially “film-like” by anyone. Each layman will note that the “X files” filmed on 35 mm film look somehow otherwise.
As already indicated, the depth of focus is critically influenced by the size of the recording area. A conventional 35 mm film negative is huge compared to the recording chip of a video camera. This size makes it possible that the depth of focus decreases. On the contrary, the video film-maker fails to achieve a desired lack of depth of focus due to the small area of the chip.
With regard to the fact that the resolution and the contrast of video cameras are almost daily improved, the lack of depth of focus is currently the unsolved problem of video cameras. From the company Canon it is known to place photo optics in front of a video camera by means of an adapter. However, this results in the chip being much too small with regard to the film optics, to show only a detail of the projected image. The effect arising thereby is that the focal length of the optics seems to extend. Optics representing a normal objective with respect to cameras, becomes a teleobjective on a video camera.
In order to obtain the same image detail on the small chip of the video camera, which is achieved by a film camera having any optics, unequally much more wide-angled optics have to be used (approximately 7-times). This is possible, however, the achieved lack of depth of focus is thereby lost, since this one is inseparably associated with the actual length of the focal length. Namely, it is true: the smaller the formed image and the shorter the focal length of the optics, which is required for imaging a certain image detail thereon, the larger the depth of focus.
Therefore, the present invention is based on the object of developing a video camera of the initially mentioned type such that achieving low depths of focus is made possible.